An end block for a magnetron device having a rotatable target and a vacuum coating apparatus having a magnetron device of this type are described hereafter, which are simply constructed and maintenance-friendly.
So-called rotatable magnetrons are known in vacuum coating technology, in which a typically tubular target encloses a magnetic device, the tubular target being mounted so it is rotatable and being drivable, so that the target material is ablated uniformly. The tubular target is typically fastened between two end blocks in the vacuum chamber of a vacuum coating apparatus, which are designed so that they each allow the rotatable mounting of the tubular target. Different functions are typically assigned to the two end blocks for this purpose. One of the end blocks is typically implemented as a supply block for supplying the magnetron with cooling water and electrical power and the other end block is implemented as a drive end block for introducing a torque to generate the rotation of the tubular target.
Known end blocks, both supply end blocks and also drive end blocks, are typically connected fixed to a support unit, such as the chamber wall or the chamber cover of a vacuum coating apparatus, either directly or via a spacer part, which is used to influence the spacing between magnetron and substrate. End blocks of this type are known, for example, from DE 10 2007 049 735 A1 and WO 2007/147757 A1. Therefore, the spacing between the two end blocks is predefined fixed on the basis of the target length, which is predetermined by the application. However, the free space between the end blocks which is available for the target mounting is restricted greatly by this fixed spacing of the end blocks. Unequal spacings to the dark field shields typically provided on the end blocks may result at the ends of the target. Upon processing-related heating of the target tube and the length expansion resulting therefrom, the dark field spacing changes on one side and the engagement point of the coupling element, which is typically fastened on the end of the target in order to tap the torque from a drive shaft, is displaced. In addition, the length of the target tubes must be within very narrow tolerances.